1. Field of the Invention
The present invention relates to a CD (Compact Disk) player, and more particularly, to a CD player capable of playing back a partially recorded, additionally recordable CD-R (CD Recordable).
2. Description of the Related Art
The CD is well known as a recording medium to record acoustic information or the like. The CD has a lead-in area LIA where index information of recorded information is recorded, a program area PA where actual musical information is recorded, and a lead-out area LOA indicating the end of the program area PA, formed thereon in the named order from the inner periphery of the disk, as shown in FIG. 1(a). Those areas LIA, PA and LOA as a whole are called an information area. A signal to be recorded is a digital signal modulated by EFM (Eight to Fourteen Modulation), and includes a main code (main information) such as musical information, and a sub code such as a time code (time information). Index information called TOC (Table Of Contents) is recorded in the lead-in area LIA, and the total number of recorded information pieces (e.g., the total number of musical titles, the total program time (e.g., the total playing time), etc. are recorded as a sub code also in that area LIA. Musical information or the like is recorded as a main code in the program area PA. A track number (TNO) indicating the number of each piece of recorded information (e.g., the music number), the program time (P-TIME) from the beginning of the track, such as the playing time of the music piece, the total program time (A-TIME) measured from the first track number (=1), such as the total playing time, etc. are recorded in the Q channel of the sub code in the program area PA. In the lead-out area LOA is recorded a lead-out code indicating the lead-out area.
In a CD player that plays back the above CD, when the CD is set, a pickup is moved to a predetermined position (home position), a setup operation is then performed to rotate the CD to make it ready for information reading therefrom, and TOC information is read from the lead-in are upon completion of the setup operation. Since the TOC information normally includes the track number of the last piece of recorded information in the program area (LTNO), a playback instruction of recorded information beyond the LTNO, even if given, will not be accepted. In some cases, however, reading the TOC information is rendered impossible, e.g., due to scratches on the disk. If reading of the TOC information is not possible, the LTNO cannot be acquired in advance, so that when an instruction to reproduce the last piece of recorded information is issued, searching for the LTNO is executed.
The operational diagrams illustrating a process in the search for the LTNO are given in FIG. 2(a) to FIG. 2(d). In the search for the LTNO, the target TNO is set to the maximum TNO "99" and searching is conducted radially outward first by means of track jumps. A track-jump (hereinafter referred to as "Tr-jump") is a skip of tracks in reproduction of the disk. The search speed is generally improved by the Tr-jump by skipping over about 100 recorded tracks on a disk at a time. When 99 pieces of information are not recorded, the lead-out area is detected in this search as apparent from (a) in FIG. 2. When the lead-out area is detected, the search is terminated and back 10 Tr jumps (jumps each skipping back ten tracks) are performed until the program area is detected as indicated in (b) in FIG. 2. A 10 Tr jump is such that its jump-over time is equal to or smaller than the predetermined minimum recording time (e.g., 4 seconds) for one piece of information. Therefore, the area in the program area that is detected after the 10 Tr jump is the recording area for the last piece of recorded information, and the TNO indicated by the sub code which is read out from that area is the LTNO. Accordingly, the LTNO is detected and memorized, and the pickup is moved to the head of the information specified by the TNO of the detected LTNO to reproduce the last piece of recorded information, as indicated in (c) in FIG. 2. Thereafter, searching is conducted referring to the memorized LTNO.
The CD player which plays back the above-described CD sequentially reads the recorded information in the program area outward from the inner periphery in normal playback mode. Heretofore, the detection and control of the end of recorded information in the program area (hereinafter called "disk-end") in such playback or fast forward (FF) mode is performed in such a way that the last track number (LTNO) of the information recorded in the program area is previously acquired from the TOC information and controllably memorized. It is then discriminated as the disk-end:
1. When the lead-out area is detected, or PA1 2. When a track number larger than the LTNO is detected.
FIG. 3 illustrates a flowchart of a routine for determining the disk-end in playback mode in the prior art. During playback, as information is read out, sub codes are sequentially read out. First, the currently acquired sub code is compared with the previously obtained sub code (step S50). If both sub codes equal each other, step S50 is repeated; and if both differ from each other, the current sub code is stored in the memory area of the previous sub code (step S51). Then, it is determined from the sub code information if the pickup has entered the lead-out area (step S52). When the pickup is in the lead-out area, it is discriminated as the disk-end and the routine goes to the subsequent control process of moving the pickup 2 to access the information (disk edge) of the first track number (FTNO) recorded at the innermost track of the program area. When the pickup is not in the lead-out area, on the other hand, the current track number indicated by the sub code is compared with the LTNO (step S53). When the current track number is equal to or smaller than the LTNO, the routine returns to step S50 to repeat the above sequence of processes. When the current track number is larger than the LTNO, it is discriminated as the disk-end and the subsequent process to move the pickup to the disk edge is performed as done after step S52. The conventional CD player discriminates the disk-end in the above manner.
While a CD having the above-described recording format is a read-only recording medium, an additionally recordable CD-R (i.e., a CD on which additional information can be recorded) having the same format as the CDs has been developed recently. This CD-R recording format standard is standardized into a so-called "Orange Book" and conforms to the CD format standard (called a "red book"). The CD-R disks are classified into the following three types as shown in FIG. 1(b) to FIG. 1(d) depending on the recording status of the disk.
FIG. 1(b) shows, in section, a blank or unrecorded disk where no information has yet been recorded.
FIG. 1(c) shows a section of a partially recorded CD-R disk (hereinafter referred to as "PRD") where information is partially written (i.e., the disk has been partially filled with information).
FIG. 1(d) shows a section of a finalized CD-R disk for which recording is complete and which has finally been formatted in nearly the same format as standard prerecorded CDs.
As illustrated in FIG. 1(b) to FIG. 1(d), the lead-in area LIA, program area PA and lead-out area LOA are also formatted on each CD-R in the same manner as that of CDs.
A pregroove is formed on the recording track of a CD-R, and it is wobbled by a frequency that is acquired through FM modulation of a carrier with data indicating the absolute time information (ATIP: Absolute Time In Pregroove). In a CD-R recording and playback apparatus, the tracking control and spindle control are performed according to the pregroove so that information is recorded on and read from a blank disk as well as a PRD. A PMA (Program Memory Area) as a temporary TOC area to store the recording history of recorded information is provided on the PRD at the inner periphery side of an area I that is reserved for the lead-in area LIA as indicated in FIG. 1(c). In this PMA the following three types of information are recorded. The first information includes the start and end addresses of information recorded in the program area, which are recorded in the same format as TOC information that is recorded in the lead-in area. The second type is disk identification information (optional) which may be 6-digit numeral information to identify a disk as needed. The third type is skip command information and skip release information, which are associated with a command to skip the recorded information piece (track) by piece or part of each piece (track) of the recorded information (time designatable in the latter case) at the time of playing back the disk. The reason for recording such information as temporary TOC in the PMA is that since information is writable in the remaining program area PA on the PRD, TOC information cannot be recorded in the lead-in area LIA until the finalization of recording is eventually instructed.
In a PRD, no information is written in an area I for the lead-in area LIA and an area O for the lead-out area LOA. Therefore, those areas remain in a mirror-finished state. When a command for finalization is given, the CD-R recording apparatus records predetermined information and TOC information recorded in the PMA as a sub code in the area I for the lead-in area LIA, and records a predetermined lead-out code indicating the lead-out area LOA in the area O for the lead-out area LOA in order to provide a format analogous to that of standard CDs. This allows conventional CD players to play back the finalized CD-R.
While the conventional CD player is capable of playing back a finalized CD-R, the player is not designed to cope with a PRD, so that it cannot reproduce reproducible information from a PRD even though information is stored in the program area PA. To describe in detail, it is so because of the following reasons. Although a PRD has TOC information recorded in the PMA provided on the inner periphery side of the lead-in area, the conventional CD player is equipped with no mechanism to access that PMA. In addition, the area I for the lead-in area LIA and the area O for the lead-out area LOA remain mirror-finished and the conventional CD player is not designed to perform the proper control on information reading from such areas so that runaway of the servo system may occur in reading information from those areas.
As a solution to this problem, the CD player may be equipped with a mechanism to access the PMA and some means to read the pregroove and perform the tracking and spindle controls, as is found in the CD-R recording and playback apparatus. The provision of such means only for the PRD is not cost effective.
The conventional CD player recognizes the recording end of a disk, which is currently being played back, by detecting the lead-out area during playback or fast forward mode, or detecting a track number (TNO) larger than the last track number (LTNO) indicating the last piece of recorded information based on TOC information previously stored during playback mode (see FIG. 3). After such recognition, the CD player performs repetitive playback or the like, starting from the recording start position of the disk. A CD player having an auto-changer capable of automatically playing back a plurality of disks would generally perform a disk exchange.
Even if the conventional CD player accesses the program area PA of a PRD, it cannot detect the recording end of the disk due to the following reasons. First, the PRD does not have a lead-out area. Secondly, the CD player cannot read information from the PMA and cannot thus acquire the TOC information, so that it is unable to find out the last track number (LTNO) or the total recording time. The above shortcoming is described below more specifically. As shown in FIG. 4, when a defect or an unrecorded area (URA; mirror-finished portion) is detected during playback (or fast forward) mode (see (a) in FIG. 4), the setup operation is performed three times there (see (b) in FIG. 4). If the setup operation is not completed even after the third try, the Tr-jump is performed again to the position corresponding to the defect-detected position after the setup at the home position HP is complete, and then the setup operation is tried again (see (c) in FIG. 4). Accordingly, the above sequence of operations is repeated endlessly. This is because no unrecorded area URA (mirror-finished portion) should be present in the to-be-reproduced area of a CD. As such, the conventional CD player cannot recognize such a mirror-finished URA, and simply sees it as a defective portion, such as a scratch, and functions accordingly. It is to be noted that the home position of a PRD is set within the program area PA. As described above, the conventional CD player involves a first problem in that it is not designed to cope with an unrecorded area URA in playback mode (first problem).
For wider applicability of CD-Rs, a CD player capable of reproducing information from the program area of a PRD through controllable alteration has been developed. In playing back a PRD, however, the conventional CD player cannot access the PMA of the PRD and is thus unable to acquire the TOC information as mentioned above. Thus, the LTNO cannot also be obtained in advance. When an instruction to reproduce the last piece of recorded information from the program area is given, therefore, it is necessary to search for the LTNO. But a lead-out code is not recorded in an area following the information recording area of the program area of the PRD and that area is a mirror-finished area. In the conventional search, therefore, the pickup comes in the mirror-finished portion as indicated in (d) in FIG. 2, which causes the spindle to run away, requiring a further setup, and which prevents the detection of the LTNO (second problem).
In addition, when a PRD is played back by the conventional CD player, TOC information cannot be read so that the last track number LTNO of recorded information cannot be acquired in advance. The LTNO is thus obtained by searching the information. But the searched last track number LTNO may be erroneously identified as smaller than the actual last track number during the searching due to a scratch on the disk, vibration of the disk or the like, and may be memorized as such. In this case, even if there still is some information on and following the track with the memorized track number, the conventional CD player sees that track as the disk-end due to the memorized track number as mentioned earlier, so that recorded information on and following the track with the once memorized LTNO cannot be reproduced. For example, if a PRD actually having 9 pieces of music recorded is identified as having 8 pieces of music due to some circumstance, the CD player views this as the disk-end when detecting the track number of the ninth piece of music information, and cannot play back the ninth piece of music information (third problem).